Caffeine is the most commonly used drug in the world, found in coffee, tea, soda, energy drinks, over-the-counter cold medications, weight-loss aids, and chocolate. Although consumption of small to moderate doses of caffeine is thought to be safe, some users become dependent on caffeine and are unable to cut back despite problems caused by their caffeine intake. While not technically a diagnosable condition, caffeine-related disorder, or caffeine-use disorder, is listed in the DSM-5 as a condition that warrants further study because the stimulating effects and side effects of caffeine can mimic those of recreational drugs. Some people, particularly adolescents, are known to use and abuse caffeinated products such as energy drinks to achieve a "high," and to combine caffeine and alcohol for a more potent effect. Caffeine-related disorders include caffeine intoxication and caffeine withdrawal.
Although Americans commonly use caffeine, few experience problems socially and occupationally because of the habit. Nevertheless, the American Psychiatric Association recognizes caffeine intoxication as a diagnosable condition, along with caffeine-induced anxiety and sleep disorder, and caffeine withdrawal.
Many foods contain caffeine, including coffee, tea, chocolate, and carbonated beverages. So do over-the-counter medicines—pain relievers, appetite suppressants, and cold medicines. Caffeine functions as a central nervous system stimulant and also a diuretic. It is a myth that coffee will sober up an inebriated person; instead, it causes agitation. Daffeine should never be given to a frostbite or hypothermia victim. As a stimulant, caffeine can cause the heart to beat faster and hasten the effects of cold temperatures on the body.
How much caffeine is there in the foods and beverages we commonly associate with it?
- Coffee, brewed, 40 to 180 mg per cup
- Coffee, instant, 30 to 120 mg per cup
- Coffee, decaffeinated, 3 to 5 mg per cup
- Tea, American brew, 20 to 90 mg per cup
- Tea, imported brew, 25 to 110 mg per cup
- Tea, instant, 28 mg per cup
- Tea, canned iced, 22 to 36 mg per 12 ounces
- Cola and other soft drinks with caffeine, 36 to 90 mg per 12 ounces
- Cocoa, 4 mg per cup
- Chocolate milk, 3 to 6 mg per ounce
- Chocolate, bittersweet, 25 mg per ounce
Once ingested, caffeine is absorbed and distributed quickly. After absorption, it passes into the brain. Caffeine does not accumulate in the bloodstream nor is it stored in the body. It is excreted in the urine hours after it has been consumed.
The effects of caffeine on health have been widely studied—in particular, its effects on fibrocystic breast disease, conditions of the heart and blood vessels, birth defects, reproductive function, and behavior in children. The American Medical Association Council on Scientific Affairs concludes, "Moderate tea or coffee drinkers probably have no concern for their health relative to their caffeine consumption provided other lifestyle habits (diet, alcohol consumption) are moderate as well."
Light to moderate caffeine consumption does not generally lead to worrisome symptoms and, in fact, may provide some health benefits, including reduced risk of heart disease and stroke, treatment of migraine headaches, increased alertness and mental acuity, fewer symptoms of depression, and even reduced risk of dementia. For some people, these benefits may outweigh any risks or negative side effects associated with caffeine use. Overuse, however, can lead to what is known as "caffeine intoxication." Caffeine intoxication refers to recent consumption of an amount of caffeine that results in restlessness, nervousness, excitement, flushed facial skin, insomnia, increased urine production, gastrointestinal upset, irregular heartbeat, muscle twitching, jumpiness or shakiness, or any combination of these symptoms. Since caffeine affects different people in different ways, the definition of "overuse" can vary.
Although some research suggests that regular use of caffeine is more of a habit than an addiction, the fact that overuse causes physical and psychological symptoms, and withdrawal symptoms develop when people stop drinking caffeinated beverages indicates the substance has addictive qualities. Symptoms of caffeine withdrawal can include headache, significant fatigue or drowsiness, depressed mood, difficulty concentrating, and even flu-like symptoms such as nausea and muscle pain. Withdrawal symptoms typically begin 12 to 24 hours after the last caffeine dose, peak after one to two days of abstinence, and may last up to nine days.
There is no dietary requirement for caffeine. Moderate caffeine intake, however, is not commonly thought to pose a health risk. About 250 to 300 milligrams of caffeine per day is considered a moderate amount. This is roughly equivalent to three cups of coffee. More than ten 8-ounce cups per day is excessive. Caffeine poisoning from excess amounts can occur.
Caffeine is defined as a drug because it is a central nervous system stimulant. Regular use may cause a mild physical dependence but generally does not affect your physical health or social or financial well-being like other addictive substances. One study that looked at the association between caffeine and alcohol use in adolescents found, however, that young people who used caffeinated energy drinks were more likely to use alcohol in later years. This appeared to be due, in part, to lack of parental supervision and lack of early intervention.
A child's caffeine consumption should be closely monitored. Caffeinated beverages may be replacing nutrient-dense foods such as milk, and their consumption may interfere with the absorption of certain nutrients such as calcium and iron. A child may also eat less after drinking caffeine because it acts as an appetite suppressant. Since there is no nutritional value in caffeine, it is generally recommended that children avoid it. For a hyperactive child, it's imperative to eliminate caffeine from the diet as it acts as a stimulant.
Pregnant women and people with coronary heart disease or peptic ulcers may be advised by their health care provider to restrict or avoid using caffeine.
Many drugs interact with caffeine. Consult your health care provider or pharmacist about potential interactions whenever you take medications.
Since caffeine-related disorder is not recognized as a diagnosable condition, there is no standardized treatment. It is on the list of substance-related disorders that require more investigation because progressive caffeine overuse that results in a dependency could lead to negative physical, psychological, and social consequences. In case of a caffeine overdose, call your local Poison Control to assess whether hospitalization is necessary.
- National Institutes of Health
- Diagnostic and Statistical Manual of Mental Disorders, fourth edition, revised
- American Psychiatric Association
- Federal Emergency Management Agency, "Surviving the Storm"
- Caffeine and Women's Health by International Food Information Council Foundation and Association of Women's Health; Obstetric and Neonatal Nurses.